The first time the Rebbe spoke of the Mezuzah Campaign was Yud Shevat 5734, simply stating that every Jewish home should have a Kosher Mezuzah for divine protection.
A few days later on Tes-Vov Shevat 5734, the Rebbe spoke again about Mivtza Mezuzah, making it an official campaign.
Sichos Kodesh Seif Gimmel | Audio
On Chof Gimmel Iyar 5734, tragedy struck in Ma’alot. A group of Palestinians took over the local school and took children hostage, eventually murdering them after a failed IDF rescue attempt. The Rebbe ordered to inspect the Mezuzahs at the school and the amount of invalid Mezuzos found corresponded to the number of deaths.
The Rebbe took this opportunity to strengthen the Shturem in the new Mezuzah campaign, encouraging people to check their Mezuzos and encourage others to do so as well. On Shabbos Parshas Behar-Bechukosai, a few days after the tragedy, the Rebbe addressed the situation publicly:
Sichos Kodesh (Seif Alef)
Similar to the other campaigns, many people did not appreciate the Mivtza Mezuzah that Lubavitch was doing. In a Sicha from Shavous 5734, the Rebbe addressed some questions people asked on the campaign and continued to encourage people to join.
Sichos Kodesh (Seif Zayin)
A few weeks later, on Shabbos Parshas Korach, 2 Tammuz, the Rebbe explained the Maileh of Mivtza Mezuzah––that its a general Mitzvah––and discussed the Taineh of Korach that a home full of Seforim does not need a Mezuzah.
Sichos Kodesh (Seif Beis)
On Yud Beis Tammuz, ten days later, the Rebbe said a story of the Frierdiker Rebbe’s imprisonment (where he Paskened that a room doesn't need a Mezuzah) and then connected it with the Shturem of Mivtza Mezuzah.
Likkutei Sichos, Chelek 19, Eikev 5, Page 126-128
The following Shabbos, the Rebbe continued on the theme of encouraging people to join the campaign. The Rebbe spoke about getting the prime minister of Eretz Yisroel to come out with a statement on Mivtza Mezuzah.
Likkutei Sichos, Chelek 13, Hosafos
On Chof Av 5734, the Rebbe brought sources for checking your Mezuzos and debunked the opposition on it.
On Shabbos Parshas Bereishis 5735, the Rebbe spoke at great length about how putting up a Mezuzah in your house will not only protect your house but all the details of your life.
Over a year later, on Yud Gimmel Tammuz 5736, the Rebbe discussed the campaign and some concerns. Over the next few weeks, the Rebbe mentioned it in almost every single Farbrengen.
Sichos Kodesh (Seif Daled)
Advanced Mezuzah Handbook (English) Compiled by Dovid Zaklikowski